| Parameter |
Value |
| Designation |
C/2021 G2 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2024-09-09T04:56:28.515840Z |
| Orbit solution date (soln_date, UTC) |
2026-03-31T09:42:17Z |
| Obs used |
3807 |
| NEO |
- |
| M1 |
8.000 |
| K1 |
5.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2024-09-07.0000000 |
| e |
1.00025996 |
| q (au) |
4.982437 |
| a (au) |
-19166.006517 |
| i (deg) |
48.473181 |
| Ω (om, deg) |
221.095047 |
| ω (w, deg) |
343.277511 |
| M (ma, deg) |
-0.000001 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.968 + 3.052\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.968 |
| n |
3.052 |
| gf |
0.998 |
| gb |
-0.954 |
| k |
1.000 |
| δ90 |
5.893 |
| Parameter |
Symbol |
Range |
Description |
| Absolute magnitude at 1 AU from Sun and Earth |
H0 |
-5 to 20 |
Intrinsic brightness of the comet |
| Photometric slope parameter |
n |
2 to 6 |
Rate of brightness change with heliocentric distance |
| Forward scattering asymmetry factor |
gf |
0.8 to 1 |
Degree of forward scattering |
| Backward scattering asymmetry factor |
gb |
-1 to -0.5 |
Degree of backward scattering |
| Partitioning coefficient |
k |
0.8 to 1 |
Ratio between forward/backward scattering contributions |
| Dust-to-gas brightness ratio |
δ90 |
1 to 10 |
Relative contribution of dust scattering to gas emission |
Reference: EPSC-DPS2025-160
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
17:30:19.66 |
+08:00:32.7 |
HIP 85779 |
25.51 |
| 2026-03-26 12:00 |
17:30:22.97 |
+08:04:11.2 |
HIP 85779 |
22.76 |
| 2026-03-27 00:00 |
17:30:26.11 |
+08:07:49.8 |
HIP 85779 |
20.36 |
| 2026-03-27 12:00 |
17:30:29.11 |
+08:11:28.5 |
HIP 85779 |
18.44 |
| 2026-03-28 00:00 |
17:30:31.95 |
+08:15:07.3 |
HIP 85779 |
17.17 |
| 2026-03-28 12:00 |
17:30:34.63 |
+08:18:46.2 |
HIP 85779 |
16.68 |
| 2026-03-29 00:00 |
17:30:37.16 |
+08:22:25.1 |
HIP 85779 |
17.04 |
| 2026-03-29 12:00 |
17:30:39.54 |
+08:26:04.2 |
HIP 85779 |
18.20 |
| 2026-03-30 00:00 |
17:30:41.76 |
+08:29:43.3 |
HIP 85779 |
20.02 |
| 2026-03-30 12:00 |
17:30:43.82 |
+08:33:22.4 |
HIP 85779 |
22.32 |
| 2026-03-31 00:00 |
17:30:45.74 |
+08:37:01.6 |
HIP 85779 |
24.99 |
| 2026-03-31 12:00 |
17:30:47.49 |
+08:40:40.8 |
HIP 85621 |
26.89 |
| 2026-04-01 00:00 |
17:30:49.10 |
+08:44:20.0 |
HIP 85621 |
24.25 |
| 2026-04-01 12:00 |
17:30:50.55 |
+08:47:59.2 |
HIP 85621 |
21.87 |
| 2026-04-02 00:00 |
17:30:51.84 |
+08:51:38.3 |
HIP 85621 |
19.86 |
| 2026-04-02 12:00 |
17:30:52.99 |
+08:55:17.5 |
HIP 85621 |
18.33 |
| 2026-04-03 00:00 |
17:30:53.97 |
+08:58:56.6 |
HIP 85621 |
17.42 |
| 2026-04-03 12:00 |
17:30:54.81 |
+09:02:35.6 |
HIP 85621 |
17.21 |
| 2026-04-04 00:00 |
17:30:55.49 |
+09:06:14.6 |
HIP 85621 |
17.73 |
| 2026-04-04 12:00 |
17:30:56.01 |
+09:09:53.4 |
HIP 85621 |
18.91 |
| 2026-04-05 00:00 |
17:30:56.39 |
+09:13:32.2 |
HIP 85621 |
20.65 |
| 2026-04-05 12:00 |
17:30:56.61 |
+09:17:10.9 |
HIP 85621 |
22.81 |
| 2026-04-06 00:00 |
17:30:56.67 |
+09:20:49.5 |
HIP 85608 |
22.56 |
| 2026-04-06 12:00 |
17:30:56.59 |
+09:24:27.9 |
HIP 85608 |
20.94 |
| 2026-04-07 00:00 |
17:30:56.35 |
+09:28:06.2 |
HIP 85608 |
19.82 |
| 2026-04-07 12:00 |
17:30:55.96 |
+09:31:44.3 |
HIP 85608 |
19.29 |
| 2026-04-08 00:00 |
17:30:55.41 |
+09:35:22.2 |
HIP 85608 |
19.41 |
| 2026-04-08 12:00 |
17:30:54.71 |
+09:39:00.0 |
HIP 85608 |
20.15 |
| 2026-04-09 00:00 |
17:30:53.86 |
+09:42:37.4 |
HIP 85608 |
21.46 |
| 2026-04-09 12:00 |
17:30:52.86 |
+09:46:14.7 |
HIP 85608 |
23.23 |
| 2026-04-10 00:00 |
17:30:51.71 |
+09:49:51.8 |
HIP 85823 |
24.43 |
| 2026-04-10 12:00 |
17:30:50.40 |
+09:53:28.6 |
HIP 85823 |
22.85 |
| 2026-04-11 00:00 |
17:30:48.95 |
+09:57:05.2 |
HIP 85823 |
21.80 |
| 2026-04-11 12:00 |
17:30:47.34 |
+10:00:41.4 |
HIP 85823 |
21.36 |
| 2026-04-12 00:00 |
17:30:45.58 |
+10:04:17.4 |
HIP 85823 |
21.57 |
| 2026-04-12 12:00 |
17:30:43.67 |
+10:07:53.1 |
HIP 85611 |
20.78 |
| 2026-04-13 00:00 |
17:30:41.61 |
+10:11:28.4 |
HIP 85611 |
18.13 |
| 2026-04-13 12:00 |
17:30:39.41 |
+10:15:03.4 |
HIP 85611 |
15.85 |
| 2026-04-14 00:00 |
17:30:37.05 |
+10:18:38.0 |
HIP 85611 |
14.10 |
| 2026-04-14 12:00 |
17:30:34.55 |
+10:22:12.3 |
HIP 85611 |
13.11 |
| 2026-04-15 00:00 |
17:30:31.89 |
+10:25:46.1 |
HIP 85611 |
13.05 |
| 2026-04-15 12:00 |
17:30:29.09 |
+10:29:19.6 |
HIP 85611 |
13.93 |
| 2026-04-16 00:00 |
17:30:26.14 |
+10:32:52.6 |
HIP 85664 |
13.27 |